Devices of the referenced type are known. They comprise a holding element with which a hollow body, for example, a syringe or carpule, can be fixed. The hollow body thereby has at least one first and one second opening. A plug placement means is provided, which is used to insert a plug into the second opening of the hollow body. The hollow body typically comprises a cylindrical interior into which the essentially cylindrical plug is to be inserted through the second opening. If the longitudinal axes of the hollow body and the plug are aligned to one another correctly, the essentially cylindrical external surface of the plug bears against the typically cylindrical inner surface of the hollow body so that a sealing effect is produced, wherein the second opening of the hollow body is tightly closed by the plug. However, the error can occur during the placement of the plug that the plug placement means does not insert the plug into the second opening of the hollow body in the correct axial alignment. The essentially cylindrical plug is then rotated about an axis with regard to the longitudinal axis of the hollow body, which axis is perpendicular to its longitudinal axis as well as to the longitudinal axis of the hollow body. The result of this is that the essentially cylindrical circumferential surface of the plug does not bear or does not completely bear against the typically cylindrical inner surface of the hollow body, so that there is a reduced sealing effect or even no sealing effect here. If therefore the plug has a position alignment that is not correct in this respect, the second opening of the hollow body is not tightly closed. It can also occur that due to an error the plug placement means does not insert a plug into the second opening of the hollow body. Of course the second opening of the hollow body is not tightly closed in this case, either.
After the insertion of the plug into the second opening of the hollow body through the first opening of the same, a medium, for example, a pharmaceutical substance, is usually inserted. The plug then among other things should prevent this medium from being able to leak out through the second opening of the hollow body. However, if the plug has an incorrect position alignment or if no plug at all is present, if therefore the second opening of the hollow body is not tightly closed, the medium can leak out here and for example, contaminate a filling station or an entire production line that comprises at least one plug placement station and preferably one filling station. Typically, the media to be inserted into the hollow body are very expensive, so that losses due to incorrectly aligned or missing plugs are to be avoided.
In order therefore to be able to check the position alignment or the presence of the plug in the hollow body, known devices typically comprise at least one camera, which supplies pictures of the hollow body to an evaluation system. This system evaluates the images in general in a software-assisted manner in order to establish whether the plug was aligned correctly. Systems are also known that comprise optical wave guides, wherein a light beam is sent through the part of the hollow body in which the plug should correctly be arranged. A light measuring device, for example, a photodiode, is provided on the side of the hollow body opposite the optical wave guide, which light measuring device essentially detects whether a light beam traverses the hollow body. In this manner it can be established whether the plug is arranged in the hollow body at all.
Camera systems have the disadvantage of being very expensive and of requiring a complex and error-prone evaluation software. However, the actual alignment of a plug can be detected with them. In contrast, fiber optic systems are constructed much more simply and are therefore more cost-effective; they do not need any particularly complicated evaluation or control software, either. However, with their aid it is possible to detect only whether a plug has been inserted into the hollow body at all. The correct position alignment compared to the hollow body cannot be determined because the light beam used for testing can also be blocked out by a plug that was inserted into the hollow body twisted about an axis perpendicular to its longitudinal axis.